package com.xtianzhuang.www.study2019.practice.leetcode.study.hash;

import java.util.HashSet;
import java.util.Set;

public class Study {
	// "static void main" must be defined in a public class.
	public static void main(String[] args) {
		// 1. initialize the hash set
		Set<Integer> hashSet = new HashSet<>();
		// 2. add a new key
		hashSet.add(3);
		hashSet.add(2);
		hashSet.add(1);
		// 3. remove the key
		hashSet.remove(2);
		// 4. check if the key is in the hash set
		if (!hashSet.contains(2)) {
			System.out.println("Key 2 is not in the hash set.");
		}
		// 5. get the size of the hash set
		System.out.println("The size of has set is: " + hashSet.size());
		// 6. iterate the hash set
		for (Integer i : hashSet) {
			System.out.print(i + " ");
		}
		System.out.println("are in the hash set.");
		// 7. clear the hash set
		hashSet.clear();
		// 8. check if the hash set is empty
		if (hashSet.isEmpty()) {
			System.out.println("hash set is empty now!");
		}
	}
}
